One of the major objectives of small arms design is to increase the number of successive shots that may be fired without reloading. This is evidenced by the historical progression from flintlocks to revolvers to modern magazine-fed semi-automatic rifles. Our prior patents identified above disclose a cylindrical, helical feed magazine for firearms that is capable of delivering 100 rounds to a suitable firearm without interruption, and which has been subsequently manufactured in commercial quantities for .22 caliber rimmed cartridges. However, manually inserting 100 cartridges into a magazine one at a time is a tedious process. Previously available rapid loading devices and designs are not capable of properly orienting such a large number of cartridges or of successfully inserting them into a magazine without intermediate manipulations. The present invention is a new and unique improvement in the art of firearm magazine loading devices, offering substantial advantages of increased cartridge capacity, simplicity of operation, and functional reliability.